Spectroscopic and Theoretical Characterization of Through-Space Conjugation of Foldamers with a Tetraphenylethene Hinge.

Through-space conjugation is an important noncovalent interaction in artificial materials and biomacromolecules. Establishing relationships between geometry and property is of high significance to provide deeper insights into this phenomenon. In this work, we have focused on the through-space conjugation in a new class of foldamers with a folded tetraphenylethene core. We have studied its impact on the photophysical properties through experimental measurements and theoretical calculations. It is found that the through-space conjugation makes significant contributions to the short-wavelength absorption in these foldamers. Moreover, these foldamers exhibit aggregation-enhanced emission (AEE) and apparent blue shifts in their emission spectra on going from solution to aggregates. The structural changes are smaller in the aggregated state than those in the isolated state during the excited-state relaxation process, which results in lower re-organization energies. This accounts for the blueshifted and enhanced emissions in the aggregates.